Acoustic curb



April 1, 1969 R. c. GR' NHEcK ACOUSTIC CURB Filed No.v 14, 1966 INVENTOR ROBERT c. GREENHECK v ATTORNEYS,

United States Patent Int. Cl. F01n 1/10 U.S. Cl. 181-50 Claims This invention relates to an acoustic curb for use with a fan. More particularly, this invention relates to an acoustic curb having a plurality of removeably mounted aligned baffles of high sound absorption characteristics positioned in the body of the curb to define uninterrupted substantially straight flow paths therethrough. The curb is preferably installed immediately downstream of a fan; on roofs, the curb connects between the building duct and the fan.

The design enables prefabrication of a structure of high quality with the added advantage of providing a simple removable suspension system for the bafiies.

In-line sound absorbing baffles have been used previously and are exemplified by those shown in the Patent No. 3,219,143 of Nov. 23, 1965.

The instant invention produces a low resistance of about 7 percent reduction in cubic feet per minute and about a 50 percent reduction in sound or some value. The baflles themselves are self-contained permanently constructed units and are uniquely attached to the curb body to facilitate installation and removal. In this manner, cleaning, when required, or replacement is facilitated. The baflies in the form of an elongated panel include an outer envelope of perforated aluminum sheeting, end plates which serve as formers during manufacture of the unit and fiber glass wool in the envelope. Preferably, the bafiie connection means are at each end of the baflie and comprise a resilient U-shaped wire member, the bight of which is attached to the midsection of a baffle end plate with the legs engaging open-ended keyhole slots in the supporting means at the upper portion of the curb body; the legs when in engagement with said slots being in a distorted condition.

The sound curb is normally mounted between an inlet and an exhaust fan and a major use is with roof fans.

These and further objects and advantages of the present invention will become more apparent upon reference to the following specification, appended claims and drawings wherein:

FIGURE 1 is a perspective view of the baffle;

FIGURE 2 is a perspective view of the acoustic curb with the baflles in operative position;

FIGURE 3 is a fragmentary cross-sectional view of a portion of a baffle in operative position within the curb with its outer envelope removed, and

FIGURE 4 is a cross-section of the acoustic curb taken on lines 4-4 of FIGURE 2.

Referring now to the drawings, it will be seen that the instant invention includes a prefabricated baffle made up of an envelope 21 of perforated aluminum sheeting filled with fiber glass wool 22 with its ends joined to end' plates 23 and with top and bottom fins 24, 25 further rigidifying the integrated structure. The bafile 20 has a rounded downstream end 26 for reducing turbulence and for producing smooth in-line flow paths between the inlet and outlet of the curb body 27. The curb body 27 is preferably rectangular having side walls 28, the upper portions of a pair of opposed side walls having supporting means 3-1. The end portions of each baffle 20 are provided with connection means 40 which are removably connected with the supporting means 31 for rigidly positioning and suspending the bafiie 20 within the curb body 27.

Preferably, the supporting means 31 is provided by a pair of upwardly extending support flanges 33 on opposing Patented Apr. 1, 1969 side walls, each connected to the upper portion of the curb body by a U-shaped inner part 38 which extends inwardly to the inner face of the side wall 28. Each support flange 33 has a series of open-ended keyhole slots 34 predeterminedly spaced therealong. Each slot 34 includes a narrow outer passage 35 extending downwardly from the top edge of the flange seats 36 and 37 which extend substantially horizontally therefrom.

Each resilient member 40 at the end plate 23 of the baffle 20 is preferably in the form of a U-shaped wire member, the bight 41 of which extends horizontally of and is attached to the end plate 23 at about the vertical midsection thereof for stabilizing the suspended bafiie. The legs 42 of the U-shaped member 40 extend upwardly into interlocked relationship with the flange 33.

Each leg 42 includes a horizontal portion 43 and a terminal vertical portion 44, the horizontal portion 43 being seated in the slot 34 and the vertical portion extending upwardly behind the lug 45 of the flange 33 and terminating above the flange to define a handle for facilitating the manipulation of the wire member upon installalion or removal of a baffle.

Because of tolerance variations, it is preferred that the wire member 40 be pivotally mounted at its bight 41 to the baffle end plate 23, this being accomplished through the strap 46 affixed to the end panel which provides a bearing 47 for the bight.

Upon installation each keyhole slot 34 receives and seats two legs 42 and as shown in FIG. 4 the preferred embodiment involves the seating of adjacent legs of adjacent panels or batfles in each slot. The legs 42 are somewhat resilient and are normally spaced apart a distance less than the distance between adjacent inner seats of two adjacent keyhole slots 34. The legs 42, therefore, are in a distorted condition when in seated position in seats 36 and 37 exerting a force horizontally away from their respective outer passages.

The resultant structure suspends each bafile in a rigid fashion enabling no significant movement thereof as air flows through the curb.

I claim:

1. An acoustic curb for a fan comprising a curb body having an inlet and an outlet and having opposed side walls, a pair of upwardly extending support flanges disposed along the upper portions of the inner faces of a pair of opposed side walls, each flange having a series of open-ended slots predeterminedly spaced therealong, a plurality of suspended baffies, each baffle having high sound absorption characteristics and being substantially in the form of an elongated panel having end plates, resilient members attached to the end plates of each panel and removably interlocked in their respective open-ended slots, said plurality of baffles being suspended within said curb to define uninterrupted substantially straight flow paths between said inlet and outlet.

2. An acoustic curb for a fan as defined in claim 1 and wherein the resilient members for the end plates each include a U-shaped wire member, the bight of the U-shaped wire member extending horizontally and being attached to an end plate at about its vertical midsection for stabilizing the suspended bafile, and the legs of the 'U-shaped member extending upwardly to interlocked condition in said slots.

3. An acoustic curb for a fan as defined in claim 2 o and wherein each open-ended slot includes a narrow outer passage in communication with a pair of opposed inner seats extending substantially horizontally therefrom, the legs in seated position being in a distorted condition and exerting a force horizontally away from their respective outer passages, adjacent legs of adjacent U-shaped wire members for adjacent bafiles being positioned in the pair of opposed inner seats of a predetermined slot.

3 4 4 An :acoustic curb for a fan as defined in claim 3' References Cited and wherein the upper end of each leg of each U-shaped UNITED STATES PATENTS wire member includes in series a horizontal portion and a terminal vertical portion, said horizontal portion being seated in its respective seat and the top of said terminal 5 vertical portion extending above said support flange and 2,800,851 7/ 1957 Kronrad et a1. 2,847,729 8/1958 Zingone. 2,858,760 1 1/ 1958 Lathrop.

defining a handle facilitating the manipulation of the 3,219,143 11/1965 Bohanon rxefilliaelngfUz-lslgrapfiig wire member upon installation and re- ROBERT S. W ARD, IR" Primal? Examine"- 5. An acoustic curb for a fan as defined in claim 4 and 10 CL X'R.

wherein the bight of each- U-shaped member is pivotally mounted to an end plate of a baffle to facilitate installa- 9843 181 56 tion; 

1. AN ACOUSTIC CURB FOR A FAN COMPRISING A CURB BODY HAVING AN INLET AND AN OUTLET AND HAVING OPPOSED SIDE WALLS, A PAIR OF UPWARDLY EXTENDING SUPPORT FLANGES DISPOSED ALONG THE UPPER PORTIONS OF THE INNER FACES OF A PAIR OF OPPOSED SIDE WALLS, EACH FLANGE HAVING A SERIES OF OPEN-ENDED SLOTS PREDETERMINEDLY SPACED THEREALONG, A PLURALITY OF SUSPENDED BAFFLES, EACH BAFFLE HAVING HIGH SOUND ABSORPTION CHARACTERISTICS AND BEING SUBSTANTIALLY IN THE FORM OF AN ELONGATED PANEL HAVING END PLATES, RESILIENT MEMBERS ATTACHED TO THE END PLATES OF EACH PANEL AND REMOVABLY INTERLOCKED IN THEIR RESPECTIVE OPEN-ENDED SLOTS, SAID PLURALITY OF BAFFLES BEING SUSPENDED WITHIN SAID CURB TO DEFINE UNINTERRUPTED SUBSTANTIALLY STRAIGHT FLOW PATHS BETWEEN SAID INLET AND OUTLET. 